Tension control system



June 13, 1939. G, OCK 2,162,527

TENS I ON CONTROL SYSTEM Filed March 23, 1935 3 Sheets-Sheet l WITNESSES' INVENTOR MY/ara 6. 600K June 13, 1939. w COOK TENSION CONTROL SYSTEM Filed Marcgh 23, 1935 3 Sheets- Sheet 2 INVENTOR MflaraGCooK June 13, 1939.

w. G. cooK 2,162,527

TENS ION CONTROL SYSTEM Filed March 23, 1935 3 Sheets-Sheet 3 WITNESSES: INVENTOR d ,Z

7 h? MflaraG. coo/r,

Patented June 13, 1939 UNITED STATES PATENT OFFICE TENSION CONTROL SYSTEM Pennsylvania Application March 23, 1935, Serial No. 12,543

16 Claims.

My invention relates, generally, to electrical control systems and, more particularly, to systems for controlling and maintaining tension on material being worked by a mill or other work device.

In the working of various materials it has been found advantageous to subject the material whether it be metal, fiber, cloth, etc., to a predetermined amount of tension. The tension may be applied in the form of a back or retarding tension, or a pulling tension, or both kinds 'of tension may be applied at the same time, such for example, as in the operation of a reversible mill, or wire drawing machine, comprising a roll stand and reels on opposite sides thereof for winding-up and unwinding the material during the rolling process. However, it is desirable, if not necessary, in many instances, to beable to accurately adjust and maintain the desired tension at all times when needed. Heretofore, tension has been controlled by means of friction brakes and the like acting upon a reel or other device, mounted stationary with respect to the work device, which handles the material, or a dynamo-electric machine used either as a motor to subject the material to av pulling tension, or a braking generator to subject the material to a back tension. When using a dynamo-electric machine in this capacity with a reel or other work handling device which is stationary, the tension is controlled by controlling the torque of the machine in accordance with its load current by means of a regulator, for example.

It is an object of my invention, generally stated, to provide for controlling tension on .material by subjecting a movable work handling device to a biasing force'and maintaining the device at a predetermined operating position or within a predetermined operating range.

A more specific object-o1 my invention is to provide for controlling the tension to which a material is subjected by means of a movable force-actuated work handling device and maintaining the device within a predetermined operating range by controlling the functioning of the braking or driving means for the device in accordance with its movements. Another object of my invention is to provide for utilizing the movements of a movable tensioning device to maintain the device within a predetermined operating range for which it is adapted to maintain the desired tension.

A further object of my invention is to provide for controlling the functioning of a braking device or actuating device for a material handling reel in accordance with the position of the reel. A still further object of the. invention is to provide for utilizing the movements of a movable motor-actuated tensioning reel or device for controlling the speed of rotation of the reel.

The invention, accordingly, as shown in the accompanying drawings, comprises the struc-- tural features, combination of elements and arrangement of parts that will be exemplified in the structure and system hereinafter set forth and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the invention reference may be had to the following detailed description, taken in conjunction with the drawings, in which:

Figures 1, 2 and 3, taken together, constitute a diagrammatic illustration of 'a control system embodying the principal features of the inven tion.

In practicing my invention, as it may be applied to a rolling mill in which the work handling devices are in the form of movabiy-mounted reels biased in a tension producing direction by means of a constant force, I provide for controlling the functioning of the reel driving or braking means by means of a regulator device, the eifectiveness of which is determined by the position of the reel. In other words, the reel may have a normal or mean operating position, which subjects the material to the desired constant tension. If the reel is exerting a pulling tension it will travel from the normal position in one direction if the driving force becomes too great, or in the opposite direction if the driving force becomes too small. This travel or movement of the reel may be utilized to control a regulator or other control device to control the driving force in a manner to maintain the reel at or near its normal operating position. If the reel is being utilized to exert a braking or back tension, its movements may likewise be used to control a regulator or other control device to control the braking force exerted on the unwinding reel.

In addition, I provide for rendering the degree of effectiveness of the regulator dependent upon the degree of deviation of the reel from its normal position.

Referring now to Figs. 1, 2 and 3 of the drawings, which are adapted to be placed in side-toside relation in the ordernamed to illustrate a complete exempliflcation of the invention, there is shown a rolling mill of the reversible type comprising a roll stand Ill and work handling reels H and I2 on opposite sides thereof, whereby the material I3 is unwound from one reel, passed through the rolls, and wound upon the opposite reel, and vice versa, until the rolling process is completed.

The roll stand l0 may be driven by a suitable motor M which receives, variable voltage power from a. main generator |5 which may be driven in any suitable manner.

The reels H and I2 are so constructed that the tension is applied to the material by means of a constant force acting to bias the reels in a direction to tension the material. As shown, reel comprises a drum element l6 rotatably mounted on one arm of a pivoted supporting device having a suitable weight |8 adjustably mounted on the other arm. Likewise, the reel 2 com-' l9, supporting device 2| and by means of a weight, fluid pressure, or otherwise.

As shown, the reels H and I2 have a zero position which may be termed their normal or mean position, and a plurality of abnormal positions, a, b, c, d, and e, on either side of the normal position which may be referred to as the in and out positions respectively.

The reels II and I2 may be controlled by means of dynamo-electric machines 23 and 24, which are mechanically connected to the drum elements as shown and which alternately function as gen ators and motors tobrake or drive the reels, as the case may be, to cause the material to be subjected to the tension determined by the forces applied by-the weights. It is apparent that a braking action on either reel may be produced by other means such, for example, as a Prony brake or the like.

The main motor l4 and reel motors 23 and 24 may be connected to the generator I5 by means of switches 25, 25 and 21, respectively, which function in their deenergized position to connect the motor armatures in series with the dynamic braking resistors 28, 29 and 3|, respectively, in a well known manner.

The voltage of the generator l5 may be controlled in directionand amount by means of a motor-operated rheostat 32 and field reversing switches 33 and 34. The rheostat 32 comprises, generally, a resistane element 35 and a cooperating movable conta t arm 36 actuated in either direction by mearis of a reversible motor 31.

Limit'switches 38 and 33, actuated by the arm 36, control the motor circuits to limit the movement of the arm.

In order to provide for controlling the operation of the motors and generators separately and collectively, a plurality of manual controllers 4|, 42, 43 and 44 are provided. .Controllers 4| and 43 control the operation of switches 26 and 21, respectively, to operate the reel motors independently of the roll stand. The operation of these controllers also operates the proper generator field switch 33 or 34 to cause the voltage applied to the motors to be in the desired direction. Controller 42 controls switch 25 to connect the mill motor to the generator and also operate the proper generator field switch. Controller 44 is the master controller which is utilized in conjunction with a direction controller 45 to operate the mill as a unit. The master controller has four positions, namely, stop, slow, hold and fast. When actuated to either the slow, hold or fast positions, the switches 25, 26 and 21 are energized to connect the reel and mill m0- tors to the generator and one of the generator field switches 33 and 34, as determined by the setting of the direction controller 45, is also energized. If it is desired to increase the speed of the mill, the master controller is actuated to the fast position, which energizes the generator rheostat motor 31 in the proper direction over an obvious circuit to increase the excitation of the generator. When the desired speed has been reached, the controller may be actuated to the hold position to deenergize the rheostat motor 31 and the mill continues to run at this speed. In order to reduce the mill speed, the master controller is actuated to the slow position, which energizes the generator rheostat motor 31 in the opposite direction over an obvious circuit and the generator excitation is decreased. The decrease in speed is arrested by again actuating the controller to the hold" position.

A source of constant voltage power 46 is provided for energizing the control conductors X and Y which supply the necessary current for energizing the field windings, operating relays, switches and the motor-operated devices of the system.

As shown in Fig. 1,-the material |3 is wound.

upon the reel I2 and, therefore, the first operation is to pass the material through the roll stand l0, thereby causing the reel |2 to become the unwinding reel and the reel II to become the wind-up reel. In this instance, the dynamoelectric machine 23 functions as a motor to drive the drum I5 of the reel II and the machine 24 functions as a generator to brake the drum |9 of the reel |2.

In order to provide for maintaining the pulling tension exerted by the reel H and the backtension exerted by the reel |2 at a substantially constant predetermined value, provision is made for controlling the functioning of the machines 23 and 24 in such manner as to maintain the reels as near as possible in their zero or mean positions, as shown. In the case of the windup reel the speed of the motor 23 must vary in accordance with the amount of material wound upon the drum l6 and also in accordance with the linear speed of the material. The same is true of the unwinding reel |2. In the event Y that the speed of the materialincreases, the reel tends to swing in the out direction and the motor speed must be increased, in order to return it to its mean" position. Should the speed of the material I3 decrease, the reel will tend to move in the in direction and, therefore, the speed of the reel motor must be decreased. Likewise, in the case of the unwinding reel |2 when the speed of the material increases, the generator 24 must function to permit the reel to unreduce the winding speed. When the reel is caused to swing in the out" direction, the excitation of the motor must be decreased in order to increase the winding speed. When the machines 25 and 24 are functioning as braking generators their excitation must be controlled in the opposite sense, that is, when the reel swings in the in" direction, the excitation must be de-- creased, and when the reel swings in the out direction, the excitation must be increased.

In order to provide for controlling the functioning of the reel motors 29'and 24, to maintain their respective reels in or as near as possible to their mean positions, and to quickly return them to these positions, each motor is provided with a regulator system which iscontrolled in accordance with the movements of the reels.

The regulator system for the motor 23 is shown in Fig. 2 and comprises, generally, a motor-operated rheostat 41, a multi-contact circuit closer 48, a limit switch 49 and a plurality of control switches 5|, 52, 55 and 54.

The rheostat 41 comprises a main resistance element 55, which is connected in series with the field winding 55 of the reel motor 25 across the supply conductors X and Y, and a" plurality of auxiliary resistance elements 51, 58 and 59. The movable contact element 5i is actuated by a reversible motor 52 provided with a plurality of field windings 55 and 54. The limit switches 55 and 55 are provided for limiting the movement of the contact element 5|.

In this instance, the energization of the rheostat motor 52 is controlled throughout a predetermined portion 01 the range of movement of the reel in both the in" and out directions by means of the circuit closer 48. This device comprises a plurality of contact making elements 51, 55 and 59, which are actuated at a substantially constant speed by a motor 1I connected across the conductors X and Y as shown. The device 45 is so constructed that the contact element 51 closes the circuit once for every revolution, the contact element 58 twice for each revolution and contact element 59 three times for each revolution, corresponding to either the in or out a, b or c positions of the reel II.

In order to provide for rendering the contact making device 45 eflective to control the rheostat motor 82 in accordance with the position of the reel, the limit switch 49 is so constructed that it has positions in the "in and out" directions designated by a, 12 etc. corresponding to the in and out" positions of the reel.

The limit switch 49 may be actuated in accordance with the movements of the reel in any suitable manner, such for example, as by means of the position transmitting system comprising a transmitter 12 and a receiver 15' having their stator windings connected to a common. threephase source 14 and their rotor windings connected together by means of conductors 15 in a well-known manner, so that the movements of the limit switch correspond to those of the reel.

While the particular kind of a regulator system illustrated is believed to be a preferred type, it is to be understood that other forms of regulators, such for example, as a vibrating regulator controlled in accordance with the movements of the reel, may be used to equal advantage. Furthermore, regardlessoi the type of regulator used it may be actuated or controlled-by connecting it directly to the reel or it maybe remotely controlled by a position transmitting s stem as shown.

As referred to hereinbefore, the manner in which the excitation of the reel motors 29 and 24 must be controlled depends upon whether or not they are functioning as motors or generators.

Therefore, in order that a single regulator or 5 tion to be performed. In this instance, direction 0 switches 15 and 11 are provided; and are controlled by means of the direction controller 45 which, in addition, functions to render the proper one of the generator field reversing switches 33 and 94 responsive to the operation of the master 15 controller 44.

The regulator system for the reel motor 29 is shown in Fig. 3 and also comprises a motor-operated rheostat 18, a multi-contact circuit closer 19, a limit switch 8i and a plurality of control switches 82, 93, 84- and 95. The motor-operated rheostat 18 comprises a main resistance element 85 which is connected in series with the field winding 81 of the motor 24 across the supply conductors X and Y, and a plurality of auxiliary 25 resistors 88, 89 and 99. The movable contact element 9I is actuated by a motor 92 having field windings 93 and 94.

The construction of the circuit closer 19 is the same as that described hereinbefore, and

comprises, generally, the contact elements 95, 95 and 91, which are actuated by means of a motor 98. The movements of the limit switch 5i are controlled by means of a position transmitting system comprising the transmitter 99 5 and receiver I99.

Assuming that the mill has been set in operation by actuating the master controller 44 and the direction controller 45, it will be apparent that the movements of the reels II and I2 will be' immediately transmitted to their respective limit switches 49 and 5i. In the event that the reel I I is moved to the a" position in the in" direction, the corresponding movement of the limit switch 49 to the a position causes contact fingers I93 and I94 to be bridged by the segment I 92, thereby connecting the contact element 51 of the circuit closing device 45 in series with the rheostat motor 52. This circuit extends from the contact finger I99, through conductor I95, contact members I95 of the direction switch 15, which is now closed, conductor I91, limit switch 55, field winding 53, and armature of the motor 52, to conductor Y. This causes the motor 52 to actuate the rheostat 41 in such direction as to decrease the field re- 55 sistance and thereby decrease the motor speed.

In the event that the reel I I continues to move in the in direction to the b position, contact finger I95 is next engaged by the segment I 92,

which connects the contact element 58 to the 60 energizing circuit for the rheostat motor 52. In this instance, for each revolution of the circuit closer 48 the rheostat motor 52 receives three impulses of current. Should the reel continue to move in the in direction to the 11 position, 5

contact member I99 is engaged by the segment I92, thereby connecting the contact element 59 to the energizing circuit for the rheostat motor 1 52 which now receives six impulses of current for each revolution or cycle of operation of the circuit closer 45.

The limit .switch 49 functions to control the operation of the rheostat motor 52 in the opposite manner in the event that the reel I I swings in the ou direction. Thus, in the a position tive resistance.

inthe out direction, the contact fingers H9 and III are bridged by the segment II2 to connect the contact element 61 through conductor II3, contact members II4 of the direction switch 16, conductor II5, limit switch and field winding 64 to the armature oi the motor 62. As will be readily understood, this provides for actuating the rheostat in the opposite direction, which is necessary in order to decrease the excitation of the motor and thereby increase its speed. As the reel continues to swing in the out direction to positions a and b, contact fingers I I6 and I I1 are bridged successively to connect the contact elements 69 and 69 to this circuit.

In order to quickly restore the reels to their mean positions in the event that they swing beyond the 0" positions in either direction, provision is made for causing the motor-operated rheostats 41 and 19 to run continuously at an increased speed in the desired direction, and in addition, provision is made for modifying the resistance characteristics of the rheostats.

During the operations described hereinbefore, the control switches 5I through 54 in Fig. 2 were deenergized. The switches 5| and 53 are provided with normally closed back contact members Ila and 53a, which short circuit the resistance element 51 which is connected in series with the movable contact element ll of the rheostat, and therefore, this resistor is ineiiective. The resisters 59 and 59 are controlled, respectively, by the contact members 9241 and 94a of the control switches I2 and I4, thae contacts being open to render these resistors likewise ineflective.

Since the resistor 51 is connected in series'with v the movable contact element 9|, it is apparent that it may be utilized to greatly increase the eiiectivercsistance o! the rheostat. The resistors 59 and 59 are connected in parallel with the main resistor element 55, and, therefore, may be used to greatly decrease the eflective resistance of the rheostat.

In order to describe the manner in which these resistors may function, it may be'assumed that thereel II moves to the "(1 position in the out direction. This causes the contact fingers H9 and H9 oi. the limit switch 49, to be bridged by the connected segments I29 and I2I, to establish an energizing circuit for the control switch 53 which extends through the conductor I22 and contact member I29 oi the direction switch 16. The closure 01 control switch 53 causes its contact members 59a to open, which connects a portion of the resistor 51 in series-with the movable contact element 6| oi the rheostat, thereby increasing the effective resistance of the rheostat. In addition, contact members 53b are closed to connect the conductor II5 directly to the supply conductor K through contact members. I I4 and conductor 99, thereby shunting the multi-contact circuit closer 49 and connecting the rheostat motor 92 directly across the line conductors X and Y, which causes the rheostat 41 to move continuously in a-direction to increase its effec- Contact me bers 530 open to disconnect the shunting resistor I39 to increase .the speed of the rheostat motor 62.

.It is apparent that these operations quickly decrease the excitation of theme] motor 23 and thereby 'quickly return the reel to the mean position.

In the event that the reel swings to the "e position in the "out direction, the contact finger I24 of the limit switch 49 is bridged by segments I29 and III, thereby establishing an enertrol switch 54 operated to close its contact memj bers 54a and 54b. The closure of contact members 54a connects both of the resistors59 and 59 in parallel with the main resistance element 55, thereby decreasing the effective value of the rheostat.

The closure of contact members 5412 connects conductor I91 directly to conductor X and the rheostat motor 62 runs continuously in a direction to decrease the eifective resistance of the rheostat. If the reel swings to point e in the in" direction, contact finger I21 is bridged by the segment I29, to energize the control switch 52, thereby closing its contact members 52a, which short circuits the resistor element 59 leaving the element 59 connected-in parallel with the resistor 55 thereby further decreasing the effective resistance of the rheostat 41. Contact members 540 are opened to disconnect resistor I29 to increase the speed of the rheostat motor 62.

The operation of the apparatus shown in Fig. 3 which controls the reel motor 24, which is now functioning as a generator, functions in exactly the same manner as the equipment shown in Fig. 2, except that the excitation of the generator 24 is controlled in the opposite sense to that of the motor 23.

When the reel I2 swings through the positions, a, b and c in the in" direction, the contact elementsf95, 96 and 91 of the circuit closer 19 are successively connected through the contact fingers I3I, I32, I39 and I94, and the segment I35 of the limit switch 9I, conductor I36, contact .members I31, conductor I39, limit switch I48, and the field winding 94 to the armature of the motor 92, thereby causing the motor-operated rheostat to decrease the excitation of the direction to increase the excitation of the generator.

As in the case oi. the regulator shown in Fig. 2, further movement of the reel in either direction to the d and 0 positions efiects the operation of the control switches 92 through 95 to control the effectiveness of the auxiliary resistors 99, 99 and 99 to further modify the functioning of the rheostat 19.

The movement of the reel I2 to the d position in the "in direction causes the contact fingers I 5| and I 52 of the limit switch 8| to be bridged by segments I53 and I54 to establish a circuit through conductor I55 and contact members I56 for operating the control switch 94. The

closure of switch 94 efiects the opening of its contact members 84a to connect one section of the resistor 98 in series with the movable contact 9I oi the rheostat thereby increasing the eifective value of its resistance. This reduces the excitation of the generator. The closure of con- J to eflect the closure of control switch 82.

tact member 84b connects the rheostat motor 82 directly across conductors X and Y through conductors I51 and I58 and contact members I31 to cause the continuous operation of the rheostat 18 in a direction to further decrease the excitation of the braking generator 24. In addition, the opening of contact members 840 renders the resistor I58, normally connected in parallel with the rheostat motor 82, ineffective which increases the speed of the motor.

' In the event that the reel I2 moves to the e position in the fin direction, the limit switch contact finger IGI is engaged by the segment I62 Its contact members 82a open to connect the remainder of the resistor 88 in the rheostat circuit to further decrease the excitation of the braking generator.

When the reel I2 moves to position "(1 in the out direction, limit switch contact fingers I5I and I88 are bridged by segment I84 to operate control switch 85 which closes its contact members 85a to connect resistors 88 and 88 in parallel with the main resistor element 86 of the rheostat to increase the excitation of the braking generator 24. In addition, contact members 8511 are closed to connect the rheostat motor 92 directly across the supply conductors X and Y through conductor I51, contact members I48 and conductor I41, to cause the rheostat to operate continuously in a direction to further increase the excitation of the braking generator. Contact members 850 also open to disconnect resistor I65 and increase the speed of the rheostat motor.

Further movement of the reel I2 to position e in the ou direction causes the contact gfinger I86 of the limit switch to be engaged by segment I81 to operate the control switch 83. which, at contact members 83a, shunts resistor 90 and further increases the excitation of the braking generator.

In order to reverse the operation of the mill the direction controller 45 is actuated to the opposite position, thereby rendering the other one of the field reversing switches 33 and 84 responsive to the master controller 44, and deenergizing the direction switch 18 and energizing the direction switch II. As will be readily understood, the closure of the direction switch 'I'I merely reverses the direction in which the motor-operated rheostats 41 and I8 are connected to the multi-contact circuit closers 48 and I9 through their respective limit switches, so that in this instance, the regulating system associated with the reel II functions to control the machine 28 as a generator instead of a motor, and the regulating system associated with reel I2 controls the machine 24 as a motor.

In view of the foregoing, it will be readily understood that I- have provided a regulating system for maintaining tension in the operation of rolling mills and similar devices which is simple and of rugged construction, and which is well suited for applications of this kind. The invention provides for maintaining a substantially constant predetermined tension regardless of the speed of the mill or the amount of material contained on the reel at any time. The tension which is maintained is not a function of the load on the mill motor or the reel motor but, instead, is maintained by a constantly applied force which is not in any way affected by rolling conditions.

While I have shown and described a particu- .lar embodiment of my invention, it will be obvious to those skilled in the-art that changes and modifications may be made within the scope of my invention and I, therefore, aim for the appended claims to cover all such changes and modifications that fall within the true spirit and scope of my invention.

I claim. as my invention:

1. In combination, a reeling device for moving material comprising a reel rotatably mounted on a movable support having a'predetermined normal operating position and means for biasing ,the support to subject the material to a substantially constant tension, a dynamo-electric machine connected to the reel for retarding it when unwinding and driving it when winding, and continuously-operating regulator means variably responsive to the degree of movement of the reeling device from its normal operating position for controlling the excitation of the dynamo-electric machine, whereby the reel is maintained in a predetermined operating position regardless of changes in the speed of the moving material.

2. A strip mill for rolling fiexible material having in combination, a roll stand and reels on opposite sides thereof, said reels being mounted for movement toward and away from the roll stand and biased by a constant force to subject the material between the roll stand and reels to a substantially constant tension, a dynamoelectric machine connected to each reel alternately disposed to function as a braking generator or a motor depending on the direction of movement of the strip through the mill, means for controlling the excitation of each dynamoelectric machine, and continuously-operating regulator means controlled in accordance with the movements of the reels for controlling the operation of the excitation controlling means, whereby the driving or retarding force, as the case may be, exerted by the dynamo-electric machines, is so regulated as to maintain the reels in predetermined positions.

3. In combination, a winding reel for handling strip material, mounting means for the reel whereby the material is subjected to a substantially constant tension, said mounting means being movable from a predetermined mean position to other positions on opposite sides thereof, a dynamo-electric machine disposed to function as a generator to retard the rotation of the reel or as a motor to drive it dependent on whether the reel is unwinding or winding the material, and electro-responsive means for varying the degree of excitation of the dynamo-electric machine, and means for controlling the electroresponsive means in accordance with the degree of movement of the reel from the predetermined mean position.

4. In combination, a roll stand for working moving material, winding reels on opposite sides thereof for alternately winding up and unwinding the material as it is passed back and forth through the mill, each of said reels comprising a movably-mounted winding element having a mean operating position and biased by a constant force to subject the material to a substantially constant tension, a dynamo-electric machine connected in driving relation to each winding element disposed to alternately function as motors and braking generators dependent upon the direction of movement of the material, electrically operated regulator means for controlling the excitation of each dynamo-electric machine, and means responsive to the position of the winding element with respect to the mean operating position for controlling said excitation controlling means.

5. In combination, a roll stand for working moving material; winding reels on opposite sides thereof for alternately winding up and unwinding the material asit is passed back and forth through the mill, each of said reels comprising a movably-mounted winding element having a means including an electrically-operated switching device for controlling the operation of the motor-operated rheostats in accordance with the position of the winding element with respect to its normal operating position.

6. In combination, a roll stand for working moving material winding reels on opposite sides thereof for alternately winding up and unwinding the material as it is passed back and forth through the mill, each of said reels comprising a movably-mounted winding element biased by a constant force to subject the material to a tension, a dynamo-electric machine connected in driving relation to each winding element disposed to alternately function as motors and braking generators dependent upon the direction of movement of the material, electro-responsive means for controlling the excitation of each dynamo electric machine, continuously-operating means for controlling the energization of each electroresponsive means, and switch means actuated in accordance with the position of the Winding elements for selectively connecting the electro-responsive devices to their associated switch means.

7. The combination with a work device for working moving material, of a work handling device for subjecting the moving material to a tension, said device comprising a rotatable element mounted for movement toward and away from the work device and biased by a constantly applied force, electro-responsive means for controlling the speed of rotation of the rotatable element, an electrically-operated rheostat for controlling the functioning of the electro-responsive means, and continuously-operating means including a switching device controlled in accordance with the movements of the rotatable element for variably controlling the speed and direction of operation of the rheostat.

8. The combination with a work device for working moving material, of a work-handling device associated therewith ior subjecting the moving material to a tension, said work-handling device comprising a movably-mounted winding element biased by a constant force in a direction to tension the material, a dynamo-electric machine connected in driving relation to the winding element, a motor-operated rheostat for controlling-the excitation of the dynamo-electric machine, a motor-operated interrupter for con-' trolling the energization of the motor-operated rheostat, and switch means actuated in accordance with the movements of the winding element for selectively connecting the motor-operated rheostat to the interrupter dependent upon the direction of movement of the winding element.

, 9. The combination with a work device for working moving material, of a work-handling device associated therewith for subjecting the moving material to a tension, said work-handling device comprising a movably-mounted winding element biased by a constant force in a direction to tension the material, a dynamo-electric machine connected in driving relation to the winding element, electro-responsive means for controlling the excitation of the dynamo-electric machine, a continuously-operating circuit interrupter having a plurality of control elements each disposed to maintain a circuit energized for different lengths of time, and means actuated in accordance with the position of the winding element for selectively connecting the electro-responsive means to the control elements of the interrupter.

10. The combination with a roll stand for working strip material, of movably mounted winding reels on opposite sides thereof for alternately winding and unwinding material as it is passed in opposite directions through the roll stand, means for exerting a constant biasing force on the reels to tension the material, a motor connected to each reel disposed to alternately function as motors and generators dependent upon the direction of movement of the material, a motoroperated rheostat for controlling the excitation of each motor, a motor-operated circuit interrupter for variably controlling the energization of each motor-operated rheostat, and means operable in accordance with the movement of each reel for varying the effectiveness of each circuit interrupter dependent upon the degree of movement of the reels, thereby to provide for varying the excitation of the reel motors to such a degree and at a rate corresponding to the amount of movement of the reels from a normal operating position.

11. The combination with a roll stand for working strip material, of movably mounted winding reels on opposite sides thereof for alternately winding and unwinding material as it is passed in opposite directions through the roll stand, means for exerting a constant biasing force on the reels to tension the material, a motor connected to each reel disposed to alternately function as motors and generators dependent upon the direction of movement of the material, electro-responsive means for controlling the speed of each motor, a multi-element contactor device for variably controlling the energization of the electro-responsive speed controlling means, switching means operable to selectively connect the various elements of the contactor device to the ele'ctro-responsive means, and means for actuating the switching means in accordance with the movements of their respective reels.

12. The combination with a work device for producing translatory motion of a length of material, of a reel, means for supporting the reel for movement toward and away from the work device, said supporting means having a normal operating position and being subjected to a constant biasing-force to subject the material to a substantially constant tension, a dynamo-electric machine connected in driving relation to the reel, an electrically-operated rheostat for controlling the excitation of the dynamo-electric machine, electro-responsive means controlled by the movements of the reel supporting means for controlling the operation of the rheostat, said means being ineffective to change the speed of the dynamoelectric machine when the reel supporting means is in the normal operating position and being operable to vary the speed of said dynamo-electric machine to a varying degree dependent upon the amount of movement of the reel supporting means from its normal operating position.

13. The combination with a work device for working moving material, of a work-handling device associated therewith for subjecting the moving material to a tension, said work-handling device comprising a movably mounted winding element biased by a constant force to tension the material, a dynamo-electric machine connected in driving relation to the winding element, electro-responsive regulator means for controlling the speed 01' the dynamo-electric machine, and means including an electrical position-transmitting system for controlling the operation of the regulator means in accordance with the movements of the work-handling device, whereby the speed of the winding element is so controlled as to cause the work handling device to be maintained within a predetermined range of movement.

14. The combination with a work device through which material to be worked is passed, of a winding reel for receiving the material, said reel comprising a rotatable drum element mounted for movement with respect to the work device throughout a predetermined range, means for applying a constant force tending to movethe reel away from the work device to tension the material, a motor for driving the drum element, means operable to vary the speed of the reel motor, said means being adapted to eflect a variable rate of change in the motor speed, and an electrical position-transmitting system interposed between the reel and said speed controlling means for causing said speed controlling means to i'unction in accordance with the position 01.

the reel with respect to the work device.

15.' The combination with a work device for working moving material, or. a reel element-supported by a movably mounted device for handling the material, said supporting device being biased by a constantly applied force in a. direction to subject the material to a substantially constant ten.- sion and having a normal operating position, electro-responsive means for controlling the speed of the reel element, continuously-operating regulator means for controlling the speed of the electro-responsive means, said regulator means being operable to effect varying degrees of speed change of the electro-responsive means, and means responsive to the movements of the supporting device'relative to its normal operating position for controlling the continuously operating regulator means, thereby to cause said regulator device to eflect varying degrees of speed change of the electro-responsive means in accordance with the degree of movement of the supporting device from its normal operating position.

16. The combination with a work device for working moving material, of a reel for handling the material, means for supporting the reel for movement toward and away from the work device to subject the material to a substantially constant tension, said supporting means having a mean operating position and a predetermined range of movement on opposite sides thereof, a dynamo-electric machine connected in driving relation with the reel, a variable speed electroresponsive regulator device for controlling the excitation of the dynamo-electric machine, and means controlled in accordance with the movements of the reel supporting means for controlling the speed of operation of the regulator device to varying degrees in accordance with the degree of movement of the said reel supporting means,

thereby to provide for modifying the speed of the dynamo-electric machine in varying degrees dependent upon the position of the reel supporting means relative to its mean operating position.

WIILARD G. COOK. 

